Numerous types of exercise devices have, of course, been heretofore developed.
Some of these simulate the action of climbing a ladder. This type of apparatus is representatively shown and described in U.S. Pat. Nos. 4,822,029 and 5,112,043. In both of these devices, a plurality of rungs are mounted on a transversely-spaced pair of endless oval chains. Thus, as the operator attempts to climb an inclined flight, the rungs are presented to him in the form of an endless series. Moreover, both of these patents disclose means for varying the resistance to the climbing motion. For example, in U.S. Pat. No. 4,822,029, the resistance is varied as a function of the tightness of a belt around a brake wheel, somewhat analogous to the resistance afforded by a mechanical dynometer. In U.S. Pat. No. 5,112,043, the resistance to the climbing motion is provided hydraulically.
Other types of exercise devices restrict the flow of air to resist the operator's motion. Examples of this type are shown and described in U.S. Pat. Nos. 4,082,264, 4,961,570 and 4,943,049. Other types of exercise devices utilize variant types of fans. These are representatively shown and described in U.S. Pat. Nos. 4,815,951 and 4,537,396.
While these types of devices may have been suitable for their intended uses and purposes, there is believed to be a need to provide an improved exercise device which simulates the motion of climbing a ladder with a simple and alternative means for varying the resistance of the climbing motion. Thus, the amount of energy which a person must expend may be readily varied as a function of his physical ability and conditioning.